The present invention relates to toy trains or model railroads, particularly model railroads where the track layout and scenery are to precise numerical scale of the railroad equipment with a high degree of authenticity and realism. In creating such scale model railroad layouts it is desirable to reproduce the warning and safety devices employed in full scale railroading.
In particular, it is desirable to provide a model railroad layout with authentic operating signals, flashers, gates and crossing bells.
In order to provide scale grade crossing alarms and flashers for model railroad layouts, it is necessary to provide a technique or means for detecting the passage of the model train when it passes through the track section allotted for grade crossing. Heretofore, devices employed for detecting passage of the model train have included means by which a circuit was completed between the rails through the metal structure of the wheels and chassis of the model rolling stock.
Another technique which has been employed for detecting model train passage has been the use of a photo detector disposed between the model track rails and calibrated to sense the shadow of the passing train. Where it is desired to maintain operation of an alarm device while the train is in a particular block of track, it is known to employ two photocell detectors spaced along the track to show model train shadow. However, where photocell detectors have been employed, it has been found necessary to employ electromechanical relays to activate alarm devices in view of the extremely low current handling capability of the solid state photocell detectors employed.
Furthermore, it has been desired to provide in a model railroad layout, simultaneous actuation of grade crossing flashers and authentic reproduction of a full scale grade crossing alarm bell sound.
Previous techniques for providing both grade crossing flasher and alarm bells for model railroads have employed separate detector circuits and relay mechanisms for activating the flasher lights and the alarm bell devices individually.
Thus, it has been desirable to find a way or means for detecting passage of a model railroad train through a block or section of track, such as a grade crossing, and to provide for low voltage solid stage circuitry devices for controlling and activating simultaneously, a grade crossing flasher and grade crossing alarm bell without the need for relays.